1. Field of the Invention
This invention relates to a constant velocity ratio universal joint, comprising an outer joint member having in its interior a plurality of ball-receiving tracks, spaced circumferentially from one another about a rotational axis of the outer joint member and having centre lines which lie in meridian planes: an inner joint member having a plurality of ball-receiving tracks with centre lines which lie in meridian planes about a rotational axis of the inner joint member, facing the tracks in the outer joint member in pairs; a plurality of balls disposed one in each facing pair of tracks in the joint members; and a control element holding the balls with their centres in a common plane and having an external surface engaging a part-spherical guide surface of the outer joint member between the tracks thereof; the tracks in the joint members being undercut-free considered from one end of the outer joint member and the outer joint member having a joint base member attached there at said one end. Such a constant velocity ratio universal joint will hereafter be referred to as a joint of the kind specified.
2. Description of Prior Art
A joint of the kind specified is disclosed in DE-3132364C, wherein the joint base member is formed by a wheel hub part with an inserted sheet metal cap. The joint has a disadvantage, however, in that the part-spherical guide surface in the outer joint member is not undercut-free, requiring it to be produced either by a machining operation involving material removal from the interior of the outer joint member, or an extremely complicated collapsible tool for forming it in an operation which does not involve the removal of material. Further, the joint can only be assembled by over-articulating it to enable the balls to be inserted individually.
A constant velocity ratio universal joint is disclosed in DE-3209596C, wherein the outer joint member has an undercut-free guide surface engaged by the inner joint member, but, instead of the conventional ball cage, there is provided a supporting member in the form of a part-spherical shell, engaging a part-spherical guide face in the joint base member. This design has a disadvantage that when the joint is articulated only half the total number of balls are engaged by the supporting member.